Myers’ PSYCHOLOGY

(7th Ed)

Chapter 2 Neuroscience, Genetics

and Behavior

James A. McCubbin, PhDClemson University

Worth Publishers

Neural Communication

Biological Psychology branch of psychology concerned with the links

between biology and behavior some biological psychologists call themselves

behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists

Neuron a nerve cell the basic building block of the nervous system

Neural Communication Dendrite

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

Axon the extension of a neuron, ending in branching

terminal fibers, through which messages are sent to other neurons or to muscles or glands

Myelin [MY-uh-lin] Sheath a layer of fatty cells segmentally encasing the

fibers of many neurons enables vastly greater transmission speed of

neutral impulses

Neural Communication

Neural Communication

Action Potential a neural impulse; a brief electrical

charge that travels down an axon generated by the movement of

positively charged atoms in and out of channels in the axon’s membrane

Threshold the level of stimulation required to

trigger a neural impulse

Neural Communication

Cell body end of axon

Direction of neural impulse: toward axon terminals

Neural Communication Synapse [SIN-aps]

junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

tiny gap at this junction is called the synaptic gap or cleft

Neurotransmitters chemical messengers that traverse the synaptic

gaps between neurons when released by the sending neuron, neuro-

transmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse

Neural Communication

Neural Communication

Neural Communication

Neurotransmitter molecule

Receiving cellmembrane

Receptor site onreceiving neuron

Agonist mimicsneurotransmitter

Antagonistblocksneurotransmitter

End Day 2

The Nervous System Nervous System

the body’s speedy, electro-chemical communication system

consists of all the nerve cells of the body Neurons are the elementary components

– the smallest Lego pieces, if you will There are 2 major divisions of the

nervous system central nervous system peripheral nervous system

Central Nervous System (CNS) the brain and spinal cord

Peripheral Nervous System (PNS) the sensory and motor neurons that

connect the central nervous system (CNS) to the rest of the body (sense receptors, muscles, glands)

Axons carrying PNS info are bundled together in groups called nerves

3 Types of Neurons

Sensory neurons Sends info from body tissues and sensory

organs to the CNS’s brain and spinal cordMotor neurons

CNS send messages to the body’s tissuesInterneurons

CNS internal communication neurons

The Nervous System

Central(brain and

spinal cord)

Nervoussystem

Autonomic (controlsself-regulated action of

internal organs and glands)

Somatic (controlsvoluntary movements of

skeletal muscles)

Sympathetic (arousing)

Parasympathetic (calming)

Peripheral

Further Division

The PNS can be further divided downPNS can be divided into 4 more

branches of the nervous system Somatic nervous system Autonomic nervous system Sympathetic nervous system Parasympathetic nervous system

The Branches of the Peripheral Nervous System

Somatic Nervous System Controls the body’s skeletal muscles Voluntary Autonomic Nervous System Controls the glands and the muscles of the internal

organs (such as the heart) Automatic pilot, but can be overridden

2 sub-branches – sympathetic and parasympathetic Work together to keep a steady internal state Sympathetic Nervous System Arousing – if something alarms, enrages, or challenges

you Mobilizing body’s energy in stressful situations Parasympathetic Nervous System Calms the body, conserving its energy

The Sympathetic Nervous System

The Parasympathetic Nervous System

More on the CNS

Almost unimaginable wiring diagram of a very complex computer

Complex circuits that allow for learning, feeling and thinking

10 of billions of neurons communicate to make all this happen

Spinal cord is the super highway of all “talking” and “communicating” Connects the PNS to the brain Ascending fibers send info up the spinal cord Descending fibers send info down the spinal

cord

The Reflex Reflex

a simple, automatic, inborn response to a sensory stimulus

A reflex involves one simple pathway

A single sensory neuron and a single motor neuron, connected by an interneuron

Knee-jerk reflex for example

Everything goes through spinal cord

Even is spinal cord severed, reflexes can still occur below where it was severed

Skinreceptors

Muscle

Sensory neuron(incoming information)

Motor neuron(outgoing information)

Brain

Interneuron

Spinal cord

Neural Networks

Neural Networks interconnected

neural cells with experience,

networks can learn, as feedback strengthens or inhibits connections that produce certain results

computer simulations of neural networks show analogous learning

Inputs Outputs

Neurons in the brain connect with one

another to form networks

The brain learns by modifyingcertain connections in response to feedback

End Day 3

Endocrine System

The other communication systemGlands secrete chemical messengers

called hormonesHormones start in one tissue and

travel through the bloodstream to affect other tissues, including the brain

They act on the brain and influence behavior

Hormones

Some hormones are chemically identical to neurotransmitters

This makes the nervous system and endocrine systems kindred spirits

Hormones are slower than the zippy messengers of the nervous system

Their effects outlast the effects of the neurotransmitters

Hormones influence many aspects of our lives – growth, reproduction, metabolism and mood

Functions/Locations of Endocrine Glands

Pituitary – many hormones, affect other glands

Hypothalamus – are of the brain, controls pituitary

Thyroid – metabolism Parathyroids – regulate

calcium in blood Adrenal – fight or flight Pancreas – sugar in blood Ovary/Testes – male and

female sex hormones

Specific Examples of Effects

Adrenal Glands Top of kidneys Release epinephrine and norepinephrine

aka adrenaline and noradrenalineIncrease heart rate, blood pressure, blood sugarExtra surge of energy

Pituitary Glands In the core of the brain, pea-sized Controlled by hypothalamus Influence growth Master gland – controls other glands

Endocrine and Brain/Behavior

Brain (hypothalamus) pituitary other glands hormones brain

The 2 systems work so closely together than the line between them can be blurred

End Day 3

Technology and The Brain

With technology – we can now see the brain

We can also lesion (damage) tiny clusters of normal or defective brain cells

All these techniques are to psychology what a microscope was to biology and a telescope was to astronomy.

Electroencephalogram (EEG)

Brain has mental activity that gives off electrical, metabolic, and magnetic signals

These signals can now be read by science

An EEG is an amplified recording of the waves of electrical activity that sweep across the brain’s surface

Waves are measured by electrodes placed on the scalp

We can see, through waves, what wave was caused by what stimulus

“Seeing” the Brain PET (positron emission tomography) Scan

a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

Active neurons are glucose hogs MRI (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain

fMRI (functional magnetic resonance imaging) Can reveal functioning as well as structure Blood goes where the brain is active Watch the brain light up with bloodflow (see what part of the

brain is working based on certain stimuli) How the brain divides its labor

MRI Scan - Schizophrenia

The Brain Brainstem

the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull

responsible for automatic survival functions Crossover point – nerves to and from each side of the brain

crossover to connect with the body’s opposite side. Reticular formation is inside the brainstem

Finger-shaped network of neurons from the spinal cord to the thalamus

Traffic control – tells messages where to go in the brain Arousal

Begins where the spinal cord enters the skull and swells slightly to form the…

The Brain Stem

Brain Stem - Medulla

Medulla [muh-DUL-uh] base of the brainstem

(lower half) controls heartbeat,

breathing, vomiting (thanks a lot), blood pressure, sneezing, coughing, and swallowing

Autonomic functions (involuntary)

Brain Stem - Recticular Formation

Reticular formation Inside the brainstem Finger-shaped network of neurons

from the spinal cord to the thalamus Traffic control – tells messages where

to go in the brain Arousal

Brain Stem - Thalamus Thalamus [THAL-uh-muss]

the brain’s sensory switchboard, located on top of the brainstem

Joined egg-shaped structures Receives all sense messages,

except smell, and routes them the areas of the brain that deal with each sense

transmits replies to the cerebellum and medulla

Cerebellum

Cerebellum [sehr-uh-BELL-um] the “little brain” attached to the rear of the brainstemBaseball-sized, 2 wrinkled halvesit helps coordinate voluntary movement and balanceNonverbal learning and memory enabled by itJudge time, modulate emotions, discriminate sounds and textures

The Limbic System

Limbic System

Limbic System a doughnut-shaped system of neural

structures at the border of the brainstem and cerebral hemispheres

associated with emotions such as fear and aggression and drives such as those for food and sex

includes the hippocampus, amygdala, and hypothalamus.

Limbic - Amygdala Amygdala [ah-MIG-dah-la]

two almond-shaped neural clusters that are components of the limbic system and are linked to emotions

Aggression and fear Be careful though – fear and

aggression are NOT driven by just the amygdala

One link in an integrated and complicated system

Limbic - Hypothalamus Hypothalamus

neural structure lying below (hypo) the thalamus; directs several maintenance activities Eating/hunger Drinking/thirst body temperature sexual behavior

Hypothalamus secretes hormones that control the pituitary, which stimulates other glands to release other hormones that the brain wants/needs

Limbic - HypothalamusReward centers

Pleasure centersMotivates activities that are essential to

survivalReward deficiency syndrome

Alcoholism, drug abuse, and binge eating May stem from a genetically disposed deficiency in

the brain system for pleasure and well-being Leads people to crave whatever provides that

missing pleasure or relieves negative feelings

End Day 5

The Cerebral Cortex

Cerebral Cortex the intricate fabric of interconnected neural

cells that covers the cerebral hemispheres Like the bark of a tree the body’s ultimate control and information

processing center The larger cortex in mammals allow for

increased capacities for learning and thinking

Make us more adaptable It is a “thinking crown”

Glial Cells

Glial Cells cells in the nervous system that support,

nourish, and protect neurons They are like the glue that guide neural

connections, provide nutrients and insulate myelin.

Also mop up ions and neurotransmitters May play a role in learning and thinking Chat with neurons to transmit information and

memory

The Cerebral Cortex Wrinkled – the folds increase surface area 4 lobes are divided by fissures (divides)

Many functions require the interplay of several regions/lobes

Frontal Lobes involved in speaking and muscle movements and in

making plans and judgments Parietal Lobes

include the sensory cortex Occipital Lobes

include the visual areas, which receive visual information from the opposite visual field

Temporal Lobes include the auditory areas

The Cerebral Cortex

The Cerebral Cortex

Can make different motor/sensory skills happen by applying stimulation to certain areas of the cerebral cortex

Motor Cortex Runs across the top of the brain Just behind the front lobe Controls voluntary movements

Sensory Cortex Across the top of the brain, behind the motor cortex Receives incoming sensory messages Registers and processes body sensations The more sensitive an are of the body the larger

the area of sensory cortex devoted to it

The Cerebral Cortex

The Cerebral Cortex

Functional MRI scan shows the visual cortex activated as the subject looks at faces

Association Areas

Integrate information Associate various sensory inputs with stored

memories On all 4 lobes Frontal lobe association areas enable us to plan,

judge and process new memories Frontal lobes are also tied to personality Parietal lobes have association areas that enable

mathematical and spatial reasoning An area on the underside of the temporal lobe

allows us to recognize facts

The Cerebral Cortex Aphasia

impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding)

Broca’s Area an area of the left frontal lobe that directs

the muscle movements involved in speech Wernicke’s Area

an area of the left temporal lobe involved in language comprehension and expression

Specialization and Integration

Specialization and Integration

Brain activity when hearing, seeing, and speaking words

Plasticity at Work

Girl with half a brain!Amazing!http://today.msnbc.msn.com/id/3603

2653/ns/today-today_health/t/meet-girl-half-brain/#

Brain Reorganization

Plasticitythe brain’s capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development

End Day 6

Our Divided Brain

Corpus Callosum large band

of neural fibers

connects the two brain hemispheres

carries messages between the hemispheres

Corpus callosum

Our Divided Brain

The information highway from the eye to the brain

Split Brain

a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them

Split Brain

“Look at the dot.” Two words separatedby a dot are momentarily projected.

“What worddid you see?”

or

“Point withyour left hand to theword you saw.”

Disappearing Southpaws

The percentage of left-handers decreases sharply in samples of older people (adapted from Coren, 1993).

The percentage of lefties sharplydeclines with age

10 20 30 40 50 60 70 80 90Age in years

14%

12

10

8

6

4

2

0

Percentage ofleft-handedness

Brain Structures and their Functions